Field of the Invention
The invention relates to a circuit configuration for pulsed current regulation of inductive loads, including a switching device connected in series with the inductive load between two supply-voltage terminals, and a measuring device for recording a signal corresponding to a current through the inductive load.
In order to provide for pulsed current regulation of inductive loads, as is customary, for example, for speed regulation of DC motors or for switched-mode power supplies, it is often necessary to measure the amplitude of the current through the inductive load and to use that measurement to set the duty ratio of the current regulation. An example of such pulsed current regulation has been described in German Utility Model G 91 05 697.7 U1, which is assigned to the assignee of the instant application. The switched-mode power supply described in that publication has a power MOSFET which is disposed in series with a primary winding of a transformer and has a so-called shunt resistor connected in series with it toward ground. A voltage drop across that resistor is recorded as a signal which is proportional to a load current through the power MOSFET, and is fed as a regulating signal to a control device driving the power MOSFET.
A problem when recording the current in that manner is the shunt resistor which is provided in series with the power switch, because that resistor causes power loss. However, such a shunt resistor or series resistor for the inductive load was heretofore the only possibility used to record the current in the inductive load. Besides the increased power loss of the circuit configuration, such a shunt resistor often also had to be provided as a separate component previously, which it was not possible to integrate.